Method of exhausting and filling electric gaseous discharge devices



July 17, 1956 J. H. BROOKS ET AL METHOD OF EXHAUSTING AND FILLINGELECTRIC GASEOUS DISCHARGE DEVICES Filed Dec. 31, 1952 5e 75 Pol/6Hl/Acuu Pump Z- 3 Sheets-Sheet l z IbGAsANDAIR SUPPLY 7b FINE Wlcuum RJMP6 32 64/260 link JOSEPH H. BRooKs INVENTORS. LAWRENCE W. KIMBALL Arm/mixy 7, 1956 J. H. BROOK ET AL 2,755,005

METHOD OF EXHAUSTING AN ING ELECTRIC GASEOUS DISCHARGE ICES Filed Dec.51, 1952 s Sheets-Sheet 2 1 I 9 40 H i i :J

6 I 5 3 60 fl/j M INVENTOR$-.

JOSEPH H. BROOKS LAWRENCE W. KIMBALL AWUE/VE/ y 17, 1956 J. H. BROOKS ETAL 2,755,005

METHOD OF EXHAUSTING AND FILLING ELECTRIC GASEOUS DISCHARGE DEVICESFiled Dec. 51, 1952 3 Sheets-Sheet 3 IZO-V-UNE I84 |82A I 6/ 40 J U 5050 I T |7 2A Fig.6

IN VENTORS JOSEPH H. BRooKs LAWRENCE W. KIMBALL ATTORNEY METHOD OFEXHAUSTING AND FILLING ELEC- TRIC GA'SEOUS DISCHARGE DEVICES JosephHorace Brooks, West Peabody, and Lawrence Woodrufi Kimball, Bedford,Mass., assignors to Sylvauia Electric Products Inc., Salem, Mass., :1corporation of Massachusetts Application December 31, 1952, Serial No.329,018

'10 Claims. (Cl. 226-19) This invention relates to the manufacture ofelectric gaseous discharge devices and more particularly to theexhausting and filling operations performed on these devices duringtheir manufacture.

In the manufacture of electric gaseous discharge devices, such asfluorescent lamps for example, it has been the general practiceheretofore to perform the exhausting and filling operations through aslender tube, commonly called an exhaust tube, projecting from a lampmount at One end of the lamp tube and in communication with the interiorthereof. The addition of longer lamps to the fluorescent lamp line hasserved to accentuate the time factor involved in the performance ofthese operations. For example, it takes considerably longer to properlyevacuate and fill a fluorescent lamp 96 inches in length than it does toperform these same operations on a fluorescent lamp 48 inches in length.The longer the lamp, the more time-consuming the evacuation operationbecomes.

An object of this invention is to effect a marked reduction in theamount of time required to perform the exhausting and filling operationsin the manufacture of electric gaseous discharge devices.

Another object of this invention is to provide a method of and apparatusfor evacuating and filling electric gaseous discharge devices at a speedsubstantially greater than the speeds heretofore attainable.

A further object is to provide a method of and apparatus for evacuatingfluorescent lamps more thoroughly and more quickly than heretofore.

In one embodiment of our invention, an electric gaseous dischargedevice, such as a fluorescent lamp for example, is provided with atubulation at each end thereof and in communication with the interiorthereof. The exhausting and filling apparatus on which this lamp istreated has a pair of heads into which the tubulations projecting fromthe ends of the lamp are inserted. One or more lines of communicationare established to the ends of the tubulations within the heads. Theselines of communication connect one or the other or both ends of the lampas desired to one or more vacuum pumps, a source of flushing gas, asource of filling gas, and a device for dispensing mercury. One of thefeatures of the method and apparatus of our invention is theintroduction of a flushing gas into the lamp through a tubulation at oneend thereof and evacuation of the lamp through the tubulation at theother end thereof.

These and other objects, advantages and features of our invention willbe apparent to those skilled in the art from the following descriptionof a specific embodiment thereof, a specific embodiment of the apparatusbeing shown in the accompanying drawings in which:

Figure 1 is a plan view of an exhaust apparatus embodying the principlesof our invention, as applied to a fluorescent lamp.

Figure 2 is a transverse sectional view of the apparatus of Figure 1taken along the line 22 thereof.

Figure 3 is an elevational view partly in section of one nited StatesPatent Phtented July 17, 1956 of the lamp-supporting heads and themercury dispenser associated therewith.

Figure 4 is a perspective view of a lamp exhaust schedule controlmechanism employed in conjunction with the apparatus of Figures 1, 2 and3.

Figure 5 is a schematic diagram of one of the circuits employed inconjunction with the mechanism of Figure 4 to control actuation of someof the members of the ap paratus of Figures 1, 2 and 3.

Figure 6 is a schematic diagram of a portion of the circuit employed toactivate the lamp electrodes.

Referring now to Figures 1 and 2, the apparatus shown therein, withwhich the method of our invention may be employed, comprises an oven 10resting on and supported by angle-iron ways 12 on table 14, and a pairof lamp-supporting heads 16 and 18 on table 14. Head 18 is reciprocablein slide 19. The oven 10 comprises a metal case 20 provided with alining 22 of insulating material and a burner manifold 24 extendinglongitudinally thereof adjacent to the junction of the bottom and therear walls thereof. The burner manifold 24 is connected through aflexible tube 26 to a gas and air source, not shown. A rack 28 isattached to the underside of the oven 10 adjacent to each end thereof.Each rack meshes with a pinion 30 mounted on shaft 32 journaled in thesides of the angle-iron ways 12. The shaft 32 is provided with a crankhandle 34.

The oven 10 is provided with an opening 36 in the front wall thereof andan elongated slot 38 in each end wall thereof for lamp clearancepurposes. The lamp 4% comprises a lamp tube 42 with a lamp mount 44sealed thereto at each end thereof. Each lamp mount 44 has a tubulation46 formed integral therewith, projecting therefrom and in communicationwith the interior of the lamp tube 42, and a .pair of lead-wires 48, onthe inner ends of which a filamentary electrode 50 is supported, theouter ends thereof serving as the means through which the electrodes 50may be connected to a source of electrical energy.

A wall 52, of insulating material, on table 14 closes the opening 36 inthe front wall of the oven 10 when the oven 10 is disposed in engagementtherewith as in Figure 2. The wall 52 also serves as a mounting surfacefor two pairs of terminal posts 54 which extend therethrough. One end ofeach of the four terminal posts 54 is connected through a wire 56 to asource of electrical energy and the other end thereof supports aflexible metal finger 58 which engages and overlies a lamp lead-wire 43which has been bent back along the lamp tube 42.

Referring now to Figure 3, the lamp supporting head 18, which isreciprocable in slide 19, comprises a block 60 having a chamber 62therein in which a rubber washer 64 for gripping one of the tubulations4-6 is disposed, a bore 66 through which communication is establishedbetween the chamber 62 and a port 68, and a mercury dispenser 70 incommunication with the bore 66.

One end of the lamp 40 is positioned in the head 18 by threadingtubulation 46 into the rubber washer 64. The tubulation 46 is securelyheld by the rubber washer 64 and an air-tight seal is effected withinthe head 13 by the application of a compressing force to the washer 64.The rubber washer 64 is compressed tightly around the tubulation 46 andseals off the chamber 62 by the pressure of a metal washer 72thereagainst. The metal washer 72 and the ball bearings 65 in engagementtherewith are moved by the cap 67 which is threaded onto the block 6%)and is turned 'by means of arm 69 thereon to increase or release thepressure on the rubber washer 64.

The mercury dispenser 70 comprises a mercury reservoir 74 on one end ofblock 60, a mercury dispensing chamber 76 formed in the top of block 60,and a mercury dispensing pin 78 disposed in chamber 76 and having atapered end 80 which normally is seated in the fapered bottom of thechamber 76. Communication between mercury reservoir 74 and mercurydispensing chamber 76 is established by bore 82; and communicationbetween mercury dispensing chamber 76 and bore 66 is established by bore84. The mercury dispensing chamber 76 formed in the top of block 60 iscovered by a cap 86 with a rubber diaphragm 88 disposed therebetween.The cap 86 is provided with a chamber 90 therein in register withmercury dispensing chamber 76. The mercury dispensing pin 78, which isdisposed in chambers 76 and 90, has a collar 92 attached thereto, and aspring 94 concentric therewith and disposed between the collar 92 andthe tapered roof 96 of chamber 90.

A solenoid 98, mounted on a bracket 100 on slide 19, is mechanicallyconnected to the mercury dispensing pin 78 by means of a lever 102 and aspring finger lever extension 102a, one end of which lies beneath and isengagcd by pin 106 of solenoid plunger 104. The other end of lever 102is provided with an aperture therein through which the pin 78 extends.The pin 78 is provided with a head 108. A projection 110, on the top ofcap 86, serves as a fulcrum for lever 102. A screw 112 extending througha bracket 114, and a spring 116 concentric therewith and having one endthereof attached to lever 102, serve as a stop for lever 102 when themercury dispensing pin 78 is moved to its dispensing position.

The lamp-supporting head 16, disposed opposite head 18 on table 14, issimilar in construction to lamp-supporting head 18, except that it doesnot have a mercury dispenser, i. e., the head 16 is provided with arubber Washer which grips the tubulation 46, and a port and bore incommunication therewith.

Referring now to Figure 1, tube 118 connects the port 68 of thelamp-supporting head 18 to a source of inert gas such as argon, solenoidvalve 120 being disposed in the tube 118 between the head and the gassource to permit control of the flow of gas to the head. Tube 122connects lamp-supporting head 16 to tubes 124 and 126. Tube 124 isconnected to one vacuum pump and tube 126 is connected to another vacuumpump, the tubes 124 and 126 being provided with solenoid valves 128 and130 re spectively for control purposes hereinafter described.

Actuation of valves 120, 128 and 130, energization of solenoid 98 toactuate the mercury dispenser 70, and heating of the filamentaryelectrodes 50 of the lamp 40 are all controlled by the lamp exhaustschedule control mechanism shown in Figure 4, through the circuits shownin Figures and 6.

The lamp exhaust schedule control mechanism shown in Figure 4 comprisesa copper program plate 132 with a sequence layout designated generallyby the reference number 134 disposed on a face thereof, a plurality ofstationary finger switches designated generally by the reference number136 engageable by the sequence layout 134, and means, designatedgenerally by the reference numbr 138, for moving the program plate 132with respect to the stationary finger switches 136 to bring the sequencelayout 134 on the program plate 132 into engagement with the fingerswitches 136. The program plate 132, which is slidably disposed on achannel-like base 140 has a rack 142 depending from a longitudinal edgethereof which meshes with a pinion 144 on a shaft 146 journaled in thebase 140. The shaft 146 is driven by a motor 148 through an adjustablegear reduction mechanism 150, pulleys 152 and belt 154. The sequencelayout 134 comprises a plurality of strips of insulating tape 156 ofpre-determined length atfixed to the program plate 132 at pre-determinedlocations thereon in alignment with the finger switches 136. Theplurality of finger switches 136, with lead-wires 158 extendingtherefrom, are mounted on a bracket 160, and insulated from one anotherand the bracket.

Since the lamp exhaust schedule control mechanism,

as illustrated in Figure 4, is arranged to control five differentoperations, five separate electrical circuits are provided to initiateand terminate these operations. Since the circuits for controlling theoperation of solenoid valves 120, 128 and and mercury dispenser solenoid98 are identical in nature, only one of these four is illustrated, thisbeing shown in Figure 5, and only one of them will be described. Thepower source for this circuit is a transformer 162 with a 120 voltprimary and a 12 volt secondary. One end of the secondary is connectedby line 164 to the base on which the program plate 132 is disposed andthe other end of the secondary is connected through line 166 and coil168 of relay 170 to one of the lead-wires 158 connected to one of thefinger switches 136. One side of the pri mary of transformer 162 isconnected by line 172 through a coil 174 (of solenoid valve 120, 128 or130, or mercury dispenser solenoid 98, as the case may be) and line 182to an electrical contact 176 of relay 170; and the other side of theprimary is connected by line 178 to a springloaded finger 180 of relay170, the finger 180 being normally closed with respect to contact 176.

The circuit illustrated in Figure 6 is a portion of the circuit employedto effect heating of the filamentary elec trodes 50 of the lamp 40, theremainder of the circuit being the same as the circuit of Figure 5, withthe lamp circuit of Figure 6 substituted for the coil 174 of Figure 5.One leg of each of the filamentary electrodes 50 is connected throughline 172a to one side of the 120 volt pri mary and the other leg of eachof the filamentary electrodes 50 is connected through a ballast 184,such as an incandescent lamp for example, and line 182a to a relay 170.

The method of our invention, as practiced on the apparatus shown in theaccompanying drawings and described above, will now be described.Referring first to Figures 1, 2 and 3, lamp 40, which is a 40 wattfluorescent lamp, 48 inches in length and 1% inches in diameter, forexample, is positioned on the subject apparatus by threading tubulation46 at one end of lamp 40 into the aperture in the rubber washer 64 inlampsupporting head 16. Lamp-supporting head 18 is retracted on itsslide 19 a distance sufficient to permit the tubulation 46 at the otherend of the lamp 40 to be threaded into the rubber washer 64 therein. Thehead 18 is then advanced to the position shown in Figure 3 and securedin this position by manipulation of nut 21 on screw 23. The rubberwashers 64 in the heads 16 and 18 are deformed by manipulation of arms69 to securely grip the tubulations 46 and effect an air-tight seal inthe heads 16 and 18. The lamp lead-wires 48 are then bent back over theperiphery of the lamp and beneath the flexible metal fingers 58. Theoven 10 is moved forward from the position shown in Figure 1 to theposition shown in Figure 2 by rotation of the crank handle 34. Rotationof the crank handle 34 is translated into linear movement of the oven 10through shaft 32 on which the handle 34 is mounted, pinions 30 mountedon the shaft 32, and racks 28 attached to the underside of the oven 10,the oven 10 sliding on the angle-iron ways 12. As the oven 10 approachesthe wall 52, the opening 36 in the oven 10 provides clearance for thelamp tube 42 and the elongated slots 38 in the end walls of the oven 10provide clearance for the tubulations 46 projecting from the ends of thelamp tube.

With the lamp 40 in the position shown in Figure 2, and the oven 10 at atemperature high enough to insure a tube temperature during exhaust ofabout 200 C. to 350 C. for example, the lamp exhausting operation isstarted. Initiation of the lamp exhausting operation is effected byenergization of the motor 148 which drives the program plate 132 of thelamp exhaust schedule control mechanism shown in Figure 4. As theprogram plate 132 moves from left to right in Figure 2, the

sequence layout 134 thereon is carried into and out of engagement withthe stationary finger switches 136 which, through circuits like the oneshown in Figure 5, control actuation of solenoid valves 120, 128 and 130(Fig. 1) and mercury dispenser 70 (Fig. 3), and, through the circuits ofFigures 5 and 6, control heating of the filamentary electrodes 50 of thelamp 40.

When the transformer 162 is connected to a source of electrical energy,current flows through the several 12 volt circuits like the one shown inFigure 5. Each of these circuits comprises line 164, program plate 132,one of the finger switches 136, line 158, coil 168 of one of the relays170, and line 166. When current flows in the 12 volt circuits, the coil168 of each of the several relays 170 effects and maintains a break ineach of the 120 volt circuits by drawing the finger 180 away from itsnormally closed position with respect to contact 176.

When the program plate 132 reaches a point in its travel from left toright in Figure 2 where insulating tape 156a comes into contact withfinger switch 136a, this 12 volt circuit is broken and thus this 120volt circuit closes with the return of spring-loaded finger 180 of relay170 to engagement with electrical contact 176. Closing of the 120 voltcircuit and energization of coil 174 of solenoid valve 128 (Fig. 1)effects an opening of this valve and thereby places the lamp 40 incommunication with a rough vacuum pump. Rough pumping continues untilthis 120 volt circuit is broken by the movement of insulating tape 156aout of engagement with finger switch 136a.

Shortly after the 12 volt circuit through finger switch 136a has beenbroken by insulating tape 156a, the insulating tape 15611 moves intocontact with finger switch 136!) and breaks this particular 12 voltcircuit. Breaking of this 12 volt circuit effects a closing of this 120volt circuit through its relay 170, and energization of coil 174 ofsolenoid valve 120 (Fig. 1), thus placing the lamp 40 in communicationwith a supply of flushing gas. Thus, at this point, an inert gas, suchas argon for example, is being introduced into the lamp 40 at one endthereof while the lamp is being evacuated through valve 128 connected tothe other end thereof. The supply of inert gas may, for example, be at apressure of about 6 lbs/sq. in. gauge and one or more restrictions (notshown) are disposed in the line 118 to cut down the rate of flow of theinert gas to the lamp 40 and thereby reduce the pressure thereof to avalue substantially below atmospheric.

As the program plate 132 continues its travel, the insulating tape 156cthereon moves into engagement with finger switch 136c, thereby breakingthis 12 volt circuit and effecting a closing of this 120 volt circuit toheat the electrodes 50 of the lamp 40. As was described above, thecircuit for heating the electrodes 50, to break down the coating thereonwith which fluorescent lamp electrodes are normally supplied, is acombination of the circuit of Figure 6 with the circuit of Figure 5, theFigure 6 circuit being substituted for the coil 174 of Figure 5. Thus atthis point in the lamp exhaust operation the electrodes are being heatedto break down the coating thereon, a flushing gas is being introducedinto one end of the lamp through valve 120 and the lamp is beingevacuated from the other end thereof through valve 128.

After the lamp has been pumped down fairly well and most of thecontaminants therein flushed therefrom, the solenoid valve 128 is closedby the movement of insulating tape 156a out of contact with fingerswitch 136a and the consequent closing of this 12 volt circuit throughthe program plate 132 and opening of this 120 volt circuit at 176-180 inrelay 170. After the solenoid valve 128 has been closed to disconnectthe lamp 40 from the rough pump, the solenoid valve 130 is opened toconnect the lamp 40 to a fine pump. Opening of the valve 130 is effectedwhen insulating tape 156d moves into engage- 6 ment with finger switch136d, thereby opening this 12 volt circuit, closing this volt circuitthrough its relay 170, and energizing coil 174 of the valve.

Heating of the electrodes 50 is terminated by the movement of insulatingtape 156c out of engagement with finger switch 1360, and results in theclosing of this 12 volt circuit and opening of this 120 volt circuit.Pumping of the lamp 40 through solenoid valve is continued after heatingof the electrodes 50 has been discontinued. The oven 10 is thenretracted from encompassing relationship with respect to the lamp bymanipulation of the crank handle 34.

Mercury is then introduced into the lamp when insulating tape 156a movesinto engagement with finger switch 136a and thereby opens thisparticular .12 volt circuit, closes this 120 volt circuit and energizes'coil 174 of solenoid 98 (Fig. 3). The energized coil 174 draws thesolenoid plunger 104 downwardly and, through the pin 106 thereof,effects clockwise rotation of spring finger lever extension 102a andlever 102 about its fulcrum 110. Clockwise rotation of lever 102 effectsan upward movement of mercury dispensing pin 78, the displacement ofwhich permits mercury, which is at atmospheric pressure in reservoir 74,to drop from the tapered bottom of mercury dispensing chamber 76,through bore 84 and into bore 66 where the pressure is substantiallyless than atmospheric. Since flushing of the lamp with argon is takingplace at the same time that a small quantity of mercury is beingreleased by the mercury dispensing pin 78, the mercury in the bore 66 isswept into the lamp thereby.

Since the amount of mercury introduced into the lamp is relativelysmall, between about 30 to 60 milligrams for example, the making andbreaking of the 120 volt circuit to effect energization andde-energization of the solenoid coil is effected very quickly, as thelength of the insulating tape 156s indicates. If desired, a trip switchmay be incorporated in the mercury dispensing circuit to limit theeffective time this circuit is closed and thereby make sure that onlythe desired small quantity of mercury is dispensed. After the lamp hasbeen filled with the desired amount of mercury, the insulating tape 15Gbmoves out of engagement with the finger switch 136b, thereby closing the12 volt circuit therethrough, breaking the 120 volt circuit and closingthe solenoid valve 120 through which the argon was introduced to thelamp. The lamp is then pumped down through solenoid valve 130 until thepre-determined final argon pressure, such as about 3 mm. of mercury forexample, is reached, and then this valve is closed by the passage ofinsulating tape 156d out of engagement with finger switch 136d. Thiscompletes the exhausting and filling of the lamp 40, and the tubulations46 are then sealed by some suitable means, such as by a conventionalhand torch for example. The motor 148 (Fig. 4) is de-energized toterminate the travel of the program plate 132, the program plate istilted to effect disengagement of the rack 142 with its pinion 144, andthen the program plate is pulled back to starting position.

The specific lamp exhausting and filling schedule described above andillustrated by the sequence layout 134 on the program plate 132 inFigure 4 is but one of a number of schedules which may be employedsatisfactorily. The length and the relative disposition of the severalstrips of insulating tape 156 may be varied to effect such changes asmay be desired. Not only may the timing of these operations relative toone another be changed but additional operations may also be performedwithout departing from the spirit of our invention. For example, asingle valve may be employed to connect the left hand end of lamp 40 inFigure 1 to a single pump instead of using two valves to connect thisend of the lamp to two separate pumps. In some cases it may be founddesirable to have at least one pump connected to each end of the lampand exhaust alternately from one end then the other or from both ends atthe same time. Lamps may be pre-heated to the desired temperature beforethe lamp exhaust schedule cycle is initiated or they may be brought upto the desired temperature in the oven 10 during the cycle. If theformer alternative is employed, the lamp exhaust schedule may becompleted more quickly than if the latter alternative is used. We havealso found that satisfactory results may be ob tained by pre-heating thelamps to the desired bulb temperature and then carrying out theexhausting and filling operations at room temperature, i. e., withpre-heated lamps an oven 10 is not absolutely necessary.

What we claim is:

1. The method of exhausting an electric gaseous discharge device whichcomprises: heating said device; and introducing a flushing gas into saiddevice at one end thereof and simultaneously evacuating said device fromanother end thereof.

2. The method of exhausting an electric gaseous discharge device whichcomprises: heating said device; evacuating said device to a pressuresubstantially below atmospheric pressure; and then introducing aflushing gas into said device at one end thereof and simultaneouslyevacuating said device from another end thereof.

3. The method of exhausting a fluorescent lamp envelope having a mountsealed thereto at each end thereof and a tubulation projecting from eachend and in communication with the interior thereof, said methodcomprising: heating said envelope; and introducing a flushing gas intosaid envelope through the tubulation at one end thereof andsimultaneously evacuating said envelope through the tubulation at theother end thereof.

4. The method of exhausting a fluorescent lamp envelope having a mountsealed thereto at each end thereof and a tubulation projecting from eachend and in communication with the interior thereof, said methodcomprising: heating said envelope; evacuating said envelope to apressure substantially below atmospheric pressure through the tubulationat one end thereof; and then introducing a flushing gas into saidenvelope through the tubulation at one end thereof and simultaneouslyevacuating said envelope through the tubulation at the other endthereof.

5. The method of exhausting and filling an electric gaseous dischargedevice, said method comprising: heating said device; introducing aflushing gas into said device at one end thereof and simultaneouslyevacuating said device from another end thereof; introducing an inertgas into said device; and sealing the ends of said device.

6. The method of exhausting and filling a fluorescent lamp envelopehaving a mount sealed thereto at each end thereof and a tubulationprojecting from each end and in communication with the interior thereof,said method comprising: heating said envelope; introducing a flushinggas into said envelope through the tubulation at one end thereof andsimultaneously evacuating said envelope through the tubulation at theother end thereof; introducing a small quantity of mercury and an inertfilling gas into said envelope through the tubulation at an end thereof;and sealing the tabulations at each end of said envelope.

7. The method of exhausting an electric gaseous discharge device whichcomprises introducing a flushing gas into said device at one end thereofand simultaneously evacuating said device from another end thereof.

8. The method of exhausting a fluorescent lamp envelope having a mountsealed thereto at each end thereof and a tubulation projecting from eachend and in communication with the interior thereof, said methodcomprising introducing a flushing gas into said envelope through thetubulation at one end thereof and simultaneously evacuating saidenvelope through the tubulation at the other end thereof.

9. The method of exhausting and filling an electric gaseous dischargedevice, said method comprising: introducing a flushing gas into saiddevice at one end there of and simultaneously evacuating said devicefrom another end thereof; introducing an inert gas into said device; andsealing the ends of said device.

10. The method of exhausting and filling a fluorescent lamp envelopehaving a mount sealed thereto at each end thereof and a tubulationprojecting from each end and in communication with the interior thereof,said method comprising: introducing a flushing gas into said envelopethrough the tubulation at one end thereof and simultaneously evacuatingsaid envelope through the tubulation at the other end thereof;introducing a small quantity of mercury and an inert filling gas intosaid envelope through the tubulation at an end thereof; and sealing thetubulations at each end of said envelope.

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